tomn

Hello all,

After tensioning a wheel, how many threads can be showing before sone should be concerned? I'm not going for longer spokes, as they are already mine, but I could buy 14mm nipples. On some of the spokes there are four threads showing. I think that there must be eight turns into the nipple though.

Any help appreciated,
Tom

Retro Grouch 

I've got bad news for you.

Your spokes are too short. Using longer nipples might hide the threads, but it won't make the spokes thread all-the-way down to the head of the nipple. If they don't the nipples have a tendency to break there and pull out of the rim.

jacknife

Do a google search for "spoke calculators". You can find a number of web-sites that have an on-line
calculator for determining correct spoke length.

mechBgon

Yeah, get the right length of spokes so you can have a nice reliable wheelset What exactly are your wheel's specs (rim & hubs, spoke count & cross pattern)?

tomn

Thanks Retro & Jacknife, but I do think that these spoke will work for this rim/hub set. I did use two spoke calculators before I bought the spokes. The DT calculator called for 261 point something, and I bought 260's. I did find one wheel building site that stated that spokes & nipples have enough threads so that the only poroblem with building wheels with slightly short spokes was lacing them. I am still looking into the situation though.

Thanks again,
Tom

mechBgon

Is it possible that you laced the wheel one cross more than what you calculated for? On a normal wheel build with proper-length spokes (meaning, ones that'll make it to the head of the nipple), the threads disappear into standard-length nipples before they're even getting significant tension, and after being settled against the hub shell, they're relaxed enough that you could turn the nipples with your fingers.

tomn

That was a good idea. I went to check, and I do have the same number of crosses as calculated. I checked the spoke lengths, and they are 260 just like the box says.

mechBgon

What are the specs of the wheel?

Rim
Hub
Spoke count
Cross pattern

tomn

Sun Rhyno Lite 26" rim - 548 ERD

DT Swiss 540 Tandem non disk front hub - 60mm hole diameter - 34.5mm center to flange - 2.8mm spoke hole diameter.

36 hole

3 cross


I checked the DT calculator again, it called for a 261 spoke with 12mm nipples, and 260's with a 14mm nipple. It is laced now with 12mm nipples. On most spokes there are 4 threads showing, and 8 threads engaged.

powers2b

Two threads is OK
Three MAX
Buy the longer nipples

mechBgon

If you look down into the nipple from the rim bed, is the spoke at least to the bottom of the slot in the head of the nipple? Not a good idea to be building tandem wheels and not have the spoke threaded into the part of the nipple that actually bears the load to the rim.

tomn

I'm sure that the spoke isn't doen to the slot in the head. I'll look to see how close it is. I did want to add that this isn't for a tandem, but it is going on a loaded touring single.

mechBgon

My Hewlett-Packard 48G says you need 262.6mm spokes. And I've built ?hundreds of pairs? of wheels based off this baby's say-so, and usually round up 1mm if I need to make a tiebreaker decision. You want the wheel to be tour-ready, right? So chalk this up to a learning experience and pick up some 263's or 264's.

If four threads are showing, at 2 threads per millimeter, that's 2mm longer than your 260's just to get the threads into the nipples, and that's still usually not quite enough, so I'd do 263's if it were me. And that confirms what my HP 48G is saying.

Al1943

Agreed.

I use the DT calculator and round down.

Al

eubi

Classic thread theory shows that only the first three threads take the load. In reality, this is shaky.

In practice, thread engagement should be 1.5d, or 1.5 X the diameter of the thread. For example, a 1/4" screw should have a minimum engagement of 1.5 * 0.25 = 0.375

mechBgon

Having seen countless spokes with the barrel of the nipple still on them, while the head is in the rim bed after breaking off the barrel, I'm sticking with my story: get that spoke to reach at least the bottom of the nipple's screwdriver slot, preferably a bit further. Unless you view breakaway spoke nipples as beneficial, that is. Hey, different spokes for different folks...

tomn

OK, so maybe I listened to the wrong spoke length calculator. Which is quite dissapointing. How about this as an alternative to buying new spokes (DT Alpine III, sold only in boxes of 72!!!) I borrowed a 16mm long nipple today, on the rim it resulted in approximately 16 threads engaged, with about 7 threads left to start of the slot inthe end of the nipple. The spoke is not all of the way to the end of the nipple, but most of the threads are engaged.

Thanks for all of your help,
Tom

mechBgon

If they're 7 threads shy, that's 3.5mm shy and I'd get 264's so the spoke reaches the head of the nipple. Alpine III's in 264mm